This invention relates generally to a scroll shaping drum used in tire construction and relates, more particularly, to the means by which components of the shaping drum are made to follow a predetermined path as an internal air cylinder within the shaping drum is actuated or de-actuated.
The class of scroll shaping drums with which this invention is to be compared includes those which have an internal air cylinder whose inner wall is provided by the outer cylindrical surface of a sleeve member (i.e. of thin wall construction) and whose outer wall is provided by the inner surface of a roller member encircling the sleeve member. The roller member supports a plurality of linkage members which are pivotally connected thereto and which are partly responsible for the expansion and contraction of the diameter of the shaping drum as the linkage members are guided between collapsed and expanded conditions as the roller member is moved vertically along the sleeve member in response to the actuation and de-actuation of the internal air cylinder.
Furthermore, there is provided between the sleeve member and the roller member positioned thereabout a plurality of cam follower assemblies which are each anchored within the inner sleeve member by way of a hub and has a cam follower member secured about the hub. Furthermore, the cam follower members of these cam follower assemblies are slidably accepted by appropriately-shaped slots defined in the roller member so that upon actuation or de-actuation of the internal air cylinder, the roller member is urged along the length of the sleeve member as the movement of the roller member is guided by the cooperation between the cam follower members and the slots defined in the roller member.
Heretofore and after several cycles, or prolonged use, of a shaping drum of the aforedescribed class, the cam follower assemblies, and in particular, the hubs thereof, have broken in two and permitted the cam follower members thereof to free themselves from the roller member slots within which they are accepted. If, however, the cam follower members are ever freed from the roller member slots, the shaping drum is rendered inoperative.
It would be desirable to provide a new and improved shaping drum of the aforedescribed class whose cam follower assemblies are provided with an improved resistance to damage which can result from repeated cycling of the shaping drum.
Accordingly, it is an object of the present invention to provide a new and improved shaping drum having a construction which provides its cam follower assemblies with an increased resistance to damage due to repeated cycling, or prolonged use, of the shaping drum.
Another object of the present invention is to provide such a new and improved shaping drum whose construction enables its cam follower assemblies to resist forces to which the cam follower assemblies are normally exposed during use of the shaping drum.
Still another object of the present invention is to provides such a new and improved shaping drum which is uncomplicated in structure, yet effective in operation.